#include<sys/wait.h>
#include<stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include<unistd.h>
#include <sys/types.h>
int main()
{
    pid_t pid;
    pid = fork();
    if(pid < 0)
    {
        printf("%s fork error\n",__FUNCTION__);
        return 1;
    } 
    else if( pid == 0 )
    { //child
        printf("child is run, pid is : %d\n",getpid());
        sleep(5);
        exit(257);
    } 
    else
    {
        int status = 0;
        pid_t ret = waitpid(-1, &status, 0);//阻塞式等待，等待5S
        printf("this is test for wait\n");
        if( WIFEXITED(status) && ret == pid )
        {
            printf("wait child 5s success, child return code is :%d.\n",WEXITSTATUS(status));
        }
        else
        {
            printf("wait child failed, return.\n");
            return 1;
        }
    }
    return 0;
}